(a) Field of the Invention
The present invention is related to an improved structure of a control valve shutter for a burner (inter alia a stove range), and more particularly, to one that prevents grease oil from contaminating combustion air passages by guiding the diluted grease into a collector provided in an area which will not affect the airports enabling the burning of a flame.
(b) Description of the Prior Art
Ever since the use of gas as a fuel for ranges, air pollution resulting from burning coal and wood has been significantly reduced. However, even with the use of fuels such as natural gas, which will not generate smoke while burning on the range, zero combustion pollution is not possible, and the combustion efficiency of the range is compromised if foreign matters block the air passage inside the range.
The blocked air passage inside the range most frequently takes place at the shutter. As illustrated in FIG. 1 of the accompanying drawings for a general structure of a control knob on a conventional range, an air inlet pipe 13 connected to a gas source 50 protrudes from one end of a valve casing 10 and a valve shaft 12 connected to a control knob 30 extends from another end of the valve casing 10. The control knob 30 protrudes out of the control panel for regulating the air amount by dialing the valve shaft 12, an air outlet pipe 11 vertically connected to a nozzle 20 is provided on the top of the valve casing 10 between the air inlet pipe 13 and the valve shaft 12. Upon removing a coil 14 on the valve shaft 12, C-shaped locking rings 15, 16, a fan-shaped electric ignition contact 17 and a casing cover 18 as illustrated in FIG. 2, the valve shaft 12 and a shutter 19 internally connected to the valve shaft 12 inside the valve casing 10 can be pulled out. Further illustration is given in FIG. 3, where the locations of all the components in the periphery of the shutter 19 that admits the gas flux when the valve shaft 12 is turned are relative to the opening of the air inlet pipe 13, is provided in recess an air outlet port 19A for the larger flame and an air outlet port 19C for the smaller flame. The air outlet port 19C contains an air pocket 19B. Both of the air outlet ports 19A and 19C are arranged in parallel formation and abutted to each other. Both air outlet ports 19A and 19B are connected through the interior of the shutter 19 and an air passage 19D connecting through the air inlet pipe 13. The air outlet port 19C is provided at the lowest position at the center of the air pocket 19B. When the valve shaft is rotated to turn around the shutter 19 inside the valve casing, any place between the air outlet port 19A and the air pocket 19B can be regulated to a point below the air inlet pipe 13 to the control valve of the range. As illustrated in FIG. 4, when the air pocket 19B is aligned to the opening of the air inlet pipe 13C to such an extent that the flux there is greater than that of the air outlet port 19A, a smaller amount of gas flows to the nozzle 20 (illustrated in FIG. 1) through the air inlet pipe 13 to ignite the smaller flame. As illustrated in FIG. 5, when the air outlet port 19A is aligned to the opening of the air inlet pipe 13C to the extent that the flux there is greater than that of the air pocket 19B, a large amount of gas flows to the nozzle 20 (illustrated in FIG. 1) from the air outlet port 19A through the opening of the air inlet pipe 13 on the control valve of the range to ignite the larger flame.
However, to allow sufficient rotation space and spacing sealing for the shutter 19, the shutter 19 must be applied with a film of lubrication oil before being placed in the valve casing. As time passes, any grease oil therein will deteriorate and become diluted. Therefore, the grease oil film on the surface of the shutter will become diluted and flow into the air pocket 19B to block the air outlet port 19C, resulting in the malfunction of the air outlet port 19C to preventing the provision of a sufficient amount of flame. Even though the shutter may be removed for clearing purposes by wiping off the oil stains accumulated on the air outlet port 19C and re-applying a new film of grease oil, the consumer may blame this malfunction on the quality of the control knob which is detrimental to the image of the range product.
Furthermore, upon being sprayed into the nozzle through the air inlet pipe and the air outlet port 19C, the gas will be contaminated by the lubricant oil stains found on the air outlet port 19C resulting in combustion pollution as the air passage inside the range is blocked by foreign matter as described above.